Don't mean to resurrect an older thread, but I figured I would chime in.
With all the research and development that's been put into the 9mm over the past 30 years, and with all the carry and combat loads, +p hollow points, etc. I don't subscribe to the old notion that you're undergunned unless you carry a 45. I know theres guys out there, probably even some on this forum, who would fight to the death over their 45 and how its the most potent carry caliber, and thats fine, I just feel with so many compact, light, and most importantly EXTREMELY RELIABLE 9mm's that we have available today (Shield, block 43, xd come to mind) that most people are better off going with a 9mm, especially if you haven't been around the sport for a decade.
Plus 45 is expensive these days lol
EDIT:
In a haste I forgot that you weren't asking about carry. my mistake. However I still stand with the 9mm. If you're into the p226 go for the mk25